Methods and apparatuses for video compression intra prediction mode determination

Abstract

A method and system for video compression prediction mode determination is disclosed. For one embodiment of the invention, the frequency domain characteristics (FDCs) of an image block are determined. The FDCs of the image block are compared to the FDCs of each of a number of prediction modes. The prediction mode having FDCs most similar to those of the image block is then determined and selected for encoding the block. For one embodiment of the invention the FDCs of the nine 4×4 prediction modes of the H.264 standard and the FDCs of a 4×4 image block are defined using a frequency domain transform. For one embodiment of the invention, one or more additional prediction modes are evaluated, and of these, the prediction mode resulting in RD optimization is selected for encoding the block.

1. A computer implemented method comprising:
 determining the frequency domain characteristics of a 16×16 pixel image block; 
 comparing the structure of the frequency domain characteristics of the 16×16 pixel image block with corresponding structure of the frequency domain characteristics of each of a plurality of intra 16×16 image encoding prediction modes specified by a video compression standard; and 
 determining an indicated prediction mode, the indicated prediction mode having frequency domain characteristics most similar to the frequency domain characteristics of the 16×16 pixel image block; 
 determining if the frequency domain characteristics of the 16×16 pixel image block are within a specified threshold value of similarity corresponding to the indicated prediction mode; 
 encoding the 16×16 pixel image block using the indicated prediction mode got by comparing the frequency domain characteristics (FDCs) of the 4 16×16 modes with the FDCs of the current macroblock, if the frequency domain characteristics of the 16×16 pixel image block are within the specified threshold of similarity; and 
 disintegrating the 16×16 pixel image block into a corresponding number of smaller image blocks if the frequency domain characteristics of the 16×16 pixel image block are not within the specified threshold value of similarity. 
 
     
     
       2. The method of  claim 1  further comprising:
 encoding the image block using the indicated prediction mode. 
 
     
     
       3. The method of  claim 1  further comprising:
 evaluating one or more additional prediction modes associated with the indicated prediction mode; 
 effecting a rate-distortion optimization among the indicated prediction mode and the additional prediction modes; and 
 encoding the image block using the prediction mode determined optimal by the rate-distortion optimization. 
 
     
     
       4. The method of  claim 3  wherein the frequency domain characteristics of the image block are determined using a Hadamard Transform. 
     
     
       5. The method of  claim 1  wherein the video compression standard is the H.264 standard. 
     
     
       6. A system comprising:
 a processor for encoding video images; and 
 a memory coupled to the processor having stored thereon an encoding application that:
 determines the frequency domain characteristics of a 16×16 pixel image block, 
 compares the structure of the frequency domain characteristics of the 16×16 pixel image block with corresponding structure of the frequency domain characteristics of each of a plurality of intra 16×16 image encoding prediction modes specified by a video compression standard, and 
 
 determines an indicated prediction mode, the indicated prediction mode having frequency domain characteristics most similar to the frequency domain characteristics of the 16×16 pixel image block; 
 determines if the frequency domain characteristics of the 16×16 pixel image block are within a specified threshold value of similarity corresponding to the indicated prediction mode; 
 encodes the 16×16 pixel image block using the indicated prediction mode got by comparing the frequency domain characteristics (FDCs) of the 4 16×16 modes with the FDCs of the current macroblock, if the frequency domain characteristics of the 16×16 pixel image block are within the specified threshold of similarity; and 
 disintegrates the 16×16 pixel image block into a corresponding number of smaller image blocks if the frequency domain characteristics of the 16×16 pixel image block are not within the specified threshold value of similarity. 
 
     
     
       7. The system of  claim 6  wherein the encoding application encodes the image block using the indicated prediction mode. 
     
     
       8. The system of  claim 6  wherein the encoding application evaluates one or more additional prediction modes associated with the indicated prediction mode, effects a rate-distortion optimization among the indicated prediction mode and the additional prediction modes, and encodes the image block using the prediction mode determined optimal by the rate-distortion optimization. 
     
     
       9. The system of  claim 8  wherein the frequency domain characteristics of the image block are determined using a Hadamard Transform. 
     
     
       10. The system of  claim 6  wherein the video compression standard is the H.264 standard. 
     
     
       11. A nontransitory machine-readable medium having instructions stored thereon, which when executed by a processor, cause the processor to perform a method, the method comprising:
 determining the frequency domain characteristics of a 16×16 pixel image block; 
 comparing the structure of the frequency domain characteristics of the 16×16 pixel image block with corresponding structure of the frequency domain characteristics of each of a plurality of intra 16×16 image encoding prediction modes specified by a video compression standard; and 
 determining an indicated prediction mode, the indicated prediction mode having frequency domain characteristics most similar to the frequency domain characteristics of the 16×16 pixel image block; 
 determining if the frequency domain characteristics of the 16×16 pixel image block are within a specified threshold value of similarity corresponding to the indicated prediction mode; 
 encoding the 16×16 pixel image block using the indicated prediction mode got by comparing the frequency domain characteristics (FDCs) of the 4 16×16 modes with the FDCs of the current macroblock, if the frequency domain characteristics of the 16×16 pixel image block are within the specified threshold of similarity; and 
 disintegrating the 16×16 pixel image block into a corresponding number of smaller image blocks if the frequency domain characteristics of the 16×16 pixel image block are not within the specified threshold value of similarity. 
 
     
     
       12. The machine-readable medium of  claim 11  wherein the method further comprises:
 encoding the image block using the indicated prediction mode. 
 
     
     
       13. The machine-readable medium of  claim 11  wherein the method further comprises:
 evaluating one or more additional prediction modes associated with the indicated prediction mode; 
 effecting a rate-distortion optimization among the indicated prediction mode and the additional prediction modes; and 
 encoding the image block using the prediction mode determined optimal by the rate-distortion optimization. 
 
     
     
       14. The machine-readable medium of  claim 13  wherein the frequency domain characteristics of the image block are determined using a Hadamard Transform. 
     
     
       15. The machine-readable medium of  claim 11  wherein the video compression standard is the H.264 standard.